SnowLoadCheck

Macon County, IL Roof Snow Load - 20 psf

Macon County, IL: your roof's ASCE 7 snow number, in plain English

Moderate
20 psf

Macon County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. Flat and low-pitch roofs in Macon County are actually governed by ASCE 7's §7.3.4 minimum of 20 psf, not the 14 psf the ground-load formula alone would produce.

In depth, not weight: that's roughly 44 inches of fresh, light snow, 16 inches of old, settled snow, or as little as 4 inches of solid ice - snow that heavy is rare here but ice from a freeze-thaw cycle adds up far faster than the depth suggests. This is a meaningful design load - most modern-code homes handle it fine, though an addition, a carport or a flat-roofed section can be a weak spot.

Macon County at a glance

Macon County by the numbers

Nationally that's #653 out of 2,758 rated counties, the top 24%; within Illinois alone, Macon County ranks #20 of 102. That's 0.7 psf above Illinois's own county-average design load of 19.3 psf.

Macon County, FIPS 17115, is home to 100,737 people near 39.8602°N 88.9615°W. Its 20 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

Macon County's snowfall, most winters

20.7 in. a year: that's Macon County's NOAA 1991-2020 snowfall normal, measured at CISCO, IL US (16.1 mi away). See the density guide.

Before you rely on Macon County's number

Treat the Macon County figure as a starting point, not a final answer: it assumes standard occupancy, a heated structure and a moderately sheltered site, per ASCE 7-22's own defaults. Exposed terrain, an unheated building or a steeper roof all shift the real number.

For a real application, skip the county number and go straight to the ASCE 7 Hazard Tool - enter your coordinates and it returns a site-specific figure a plan reviewer will recognize. See the methodology guide.